Patent GB-566462-A (GB)
Title: Improved means for controlling the operations of the cooling gills of air-cooled aero engines
IPC: F01P7/02
Filed: 1943-08-20
Abstract: 566,462. Cooling cylinders. HURST, W. F. F. MARTIN-, BUSH, E. J., and BRITISH THERMOSTAT CO., Ltd. Aug. 20, 1943, No. 13599. [Class 7 (ii)] Means for controlling the operation of the cooling gills in air-cooled aero-engines comprises one or more bellows or other elements responsive to changes in temperature in and around the engine cylinders, a change-over switch operated by the bellows &c. and controlling the direction and rotation of an electric motor which constitutes the power unit for operating the gills, a follow-up device moved in accordance with the movement of the gills and arranged to open the switch when the gills have moved to the appropriate position, the follow-up device including a control cam having a stepped form to break up the movement of the gills into a series of steps, and auxiliary means for holding the motor circuit closed while the follower of the control cam rides over the steps thereon. A gill 44, Fig. 5, of a radial engine is rocked by a chain &c. in a box 45 in known manner and through a link 47 and arm 49 rocks a shaft 23 which grips frictionally a second shaft carrying a stepped control cam 18 and a re-setting cam 41. The cam 18 is associated with two temperature responsive bellows 1, Fig. 2, which co-operate to rock a bell-crank lever 7, carrying a blade 12 provided with a double-ended contact 13. The bellows are connected independently to the hottest parts of the engine, the hotter part taking control and either bellows functioning if the other breaks down. Movement of the blade 12 closes the contact 13 on to one or other of a pair of opposed contacts 14 on an arm 15 freely pivoted on the shaft 10 of the bell-crank lever 7, setting the operating motor into motion to open or close the gills. The gills turn the stepped cam 18 which, through a follower on the arm 15, rocks the arm opening the contacts 12, 14 as the follower rides over a step on the cam. To avoid irregular or uncertain opening of the circuit should the motion of the follower be jerky, the motor is kept in circuit by a shunt circuit across the contacts 12, 14, the shunt circuit including a switch 39 normally closed but adapted to be opened, when the follower has completely negotiated a step, by an undulating cam 37, the crest portions of which displace a push rod 38 engaging the switch 39. The motor circuit also includes a pair of " limit " switches 30, Fig. 1, normally closed, but one or other adapted to be opened, when the gills reach the end of of their permissible motion, by a pin 29 which moves in unison with the stepped cam 18. The pin 29 also closes a switch 34, 35 associated with the " limit switch which is opened when the gills are fully open, the switch 34, 35 operating a pilot light. At any time the gills may be returned to a pre-set position by closing a manually-operated switch in circuit with two switches 40 which are disposed on either side of the re-setting cam 41 moving in unison with the stepped cam 18, the cam 41 closing one or other of the switches 40 until it is brought to rest between them.